Résumé
Soil respiration influences regional carbon dynamics, yet our limited
understanding of drivers of soil respiration currently constrains robust
modeling of soil CO2 efflux. There is evidence that soil respiration
does not follow the standard Arrhenius relationship with soil
temperature at the daily scale, as used in many ecosystem models, but
demonstrates a hysteretic response. The understanding of this hysteretic
response is critical to soil carbon and greenhouse gas emission
modeling. Why soil respiration deviates from monotonic temperature
dependence may depend on lag effects and antecedent features of abiotic
and biotic drivers associated with above- and belowground process
linkages. We set up a 6 months long experiment to determine the biotic
and abiotic drivers of the hysteretic relationship between soil
respiration and soil temperature. The experiment took place at Ecotron
IleDeFrance (France) using replicated closed environmental facilities
allowing the simultaneous control of environmental conditions and
on-line measurement of ecosystem processes. We reproduced semi-arid
ecosystems using basalt soil mesocosms planted with two functional
groups of plants (shrubs and grasses) in monocultures and in a mixture.
We independently controlled above- and belowground temperatures and
rainfall intensity. The split-plot, repeated-measures design allowed for
diel aboveground and temperature cycle treatments to mimic natural
conditions or for diel cycle aboveground temperature and constant soil
temperature treatments to constrain vertical soil temperature gradients,
yet mimic natural aboveground conditions. Soil CO2 concentrations were
measured under mild and heavy precipitations conditions that represent
current and project conditions. We calculated the soil respiration every
30 minutes using the gradient method and conducted additional plant
photosynthesis measurements to better target the role of biotic factors.
Our data show that abiotic and biotic treatments affect the total soil
respiration but also diel patterns and the strength of the hysteretic
effect. This demonstrates the power of experimental approaches to
disentangle physical and biological drivers of soil respiration and
better predict future CO2 efflux from soils.
Auteurs, date et publication :
Auteurs Yann Dusza , Sabrina Juarez , Simon Chollet , Régis Ferrière , Amandine Hansart , Florent Massol , Mathieu Llavata , Jean-François Le Galliard , Enrique Pérez Sánchez-Cañete , Greg Barron-Gafford
Date : 2018
Volume : 20
Pages : 8461
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSAuteurs, date et publication :
Auteurs Simon P. K. Bowring , Matthew W. Jones , Philippe Ciais , Bertrand Guenet , Samuel Abiven
Publication : Nature Geoscience
Date : 2025
Volume : 15
Issue : 2
Pages : 135-142
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSAuteurs, date et publication :
Auteurs Johanne Lebrun Thauront , Christian Walter , Philippa Ascough , Pierre Barre , Samuel Abiven
Date : 2023
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSAuteurs, date et publication :
Auteurs Víctor Resco de Dios , Jacques Roy , Juan Pedro Ferrio , Josu G. Alday , Damien Landais , Alexandru Milcu , Arthur Gessler
Publication : Scientific Reports
Date : 2025
Volume : 5
Pages : 10975
Catégorie(s)
#ANR-Citation #CNRS #Ecotron de MontpellierAuteurs, date et publication :
Auteurs Jean-Baptiste Féret , Katja Berger , Florian de Boissieu , Zbyněk Malenovský
Publication : Remote Sensing of Environment
Date : 2025
Volume : 252
Pages : 112173
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Johanne Lebrun Thauront , Severin Luca Bellè , Marcus Schiedung , Amicie Delahaie , Marija Stojanova , François Baudin , Pierre Barré , Samuel Abiven
Date : 2024
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
Pyrogenic carbon (PyC) is a continuum of aromatic and condensed organic molecules. It represents about 15 % of organic carbon in soils and sediments1. However, there is a discrepancy in the literature regarding quantification of PyC: different methods that are currently considered as reference differ largely in their results1,2. Indeed, most methods used to quantify PyC are based on different operational principles (e.g. chemical, thermal or physical stability of PyC, molecular markers) and consequently, they do not cover the same range of the PyC continuum2. In addition, most of them are expensive and/or time consuming. Here, we propose a new PyC quantification method based on Rock-Eval® thermal analysis, thought to be rapid, inexpensive and comparable to the previous methods toolbox. Rock-Eval® thermal analysis has been successfully introduced to the field of soil carbon analysis in the last two decades and allowed to distinguish between various pools of soil carbon (inorganic carbon, stable and active organic carbon) using a single analysis of combined pyrolysis and thermal oxidation3,4. In this study, we formulate the hypothesis that Rock-Eval® thermal analysis in combination with predictive modelling is suitable to quantify PyC in soil matrices.To build and validate such a model, we chose soil samples originating from contrasting climate zones and parent material and with varying properties including clay content and mineralogy, iron oxide speciation and content, pH, cation-exchange capacity and organic carbon content. We measured PyC using a set of established methods (i.e. CTO-375, BPCA and HyPy) and acquired Rock-Eval® thermograms. Then, we identified the relevant features for PyC quantification in the thermograms by applying several machine-learning approaches. This work adds a new soil carbon pool to the ones already accessible from Rock-Eval® thermal analysis and allows an efficient and rapid quantification of PyC in soils, which is needed for large-scale studies of soil carbon pools.(1) Reisser, M.; Purves, R. S.; Schmidt, M. W. I.; Abiven, S. Pyrogenic Carbon in Soils: A Literature-Based Inventory and a Global Estimation of Its Content in Soil Organic Carbon and Stocks. Front. Earth Sci. 2016, 4 (August), 1-14. https://doi.org/10.3389/feart.2016.00080.(2) Hammes, K.; Smernik, R. J.; Skjemstad, J. O.; Schmidt, M. W. I. Characterisation and Evaluation of Reference Materials for Black Carbon Analysis Using Elemental Composition, Colour, BET Surface Area and 13C NMR Spectroscopy. Appl. Geochemistry 2008, 23 (8), 2113-2122. https://doi.org/10.1016/j.apgeochem.2008.04.023.(3) Disnar, J. R.; Guillet, B.; Keravis, D.; Di-Giovanni, C.; Sebag, D. Soil Organic Matter (SOM) Characterization by Rock-Eval Pyrolysis: Scope and Limitations. Org. Geochem. 2003, 34 (3), 327-343. https://doi.org/10.1016/S0146-6380(02)00239-5.(4) Cécillon, L.; Baudin, F.; Chenu, C.; Houot, S.; Jolivet, R.; Kätterer, T.; Lutfalla, S.; Macdonald, A.; Van Oort, F.; Plante, A. F.; Savignac, F.; Soucémarianadin, L. N.; Barré, P. A Model Based on Rock-Eval Thermal Analysis to Quantify the Size of the Centennially Persistent Organic Carbon Pool in Temperate Soils. Biogeosciences 2018, 15 (9), 2835-2849. https://doi.org/10.5194/bg-15-2835-2018.
Auteurs, date et publication :
Auteurs Johanne Lebrun Thauront , Severin Luca Bellè , Marcus Schiedung , Amicie Delahaie , Marija Stojanova , François Baudin , Pierre Barré , Samuel Abiven
Date : 2024
Pages : 16551
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
The landscapes of the Vallon de la Route and Vallon de Pradieu (France) display typical geomorphological features of the Southern French Alps, with very few or no glaciers but a wide periglacial belt that extends from 2500 to 3100 m a.s.l. These valleys are unusual in that they contain several generations of rock glaciers that, from their rooting zone to their front, have developed in a topoclimatic setting characterised by high mean insolation (southerly aspect) and relatively low altitude. In this work, we determined the present status of these landforms, and more precisely the characteristics of the icy layers within the rock glaciers, via electrical soundings and thermal measurements, which we then combined with field observations. The permafrost zones in both areas are highly fragmented, whereas ground-ice can be present in landforms previously assumed as relict on the basis of their geomorphological characteristics alone. We used an empirical relationship between rock glacier flow velocity and terrain slope to estimate the time needed for both rock glacier assemblages to reach their present size. Our analyses therefore provide at the same time a broad relative chronological framework of the landscape setting up together with an overview of the spatial patterns of ice-rich permafrost features. It also suggests a number of hypotheses for the development of these landforms; however, further work involving more accurate dating methods is required to constrain these hypotheses.
Auteurs, date et publication :
Auteurs Xavier Bodin
Publication : Geografia Fisica e Dinamica Quaternaria
Date : 2025
Volume : 36
Issue : 2
Pages : pp. 27-28
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Marine Ginouvès , Stéphane Simon , Eliane Bourreau , Vincent Lacoste , Catherine Ronet , Pierre Couppié , Mathieu Nacher , Magalie Demar , Ghislaine Prévot
Publication : The American journal of tropical medicine and hygiene
Date : 2025
Volume : 94
Issue : 1
Pages : 102-106
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs V. Médoc , T. Spataro , R. Arditi
Publication : Freshwater Biology
Date : 2025
Volume : 58
Issue : 5
Pages : 858-865